Household appliance and dispensing system for dispensing a fluid and an additive

ABSTRACT

A household appliance has a fluid dispensing system for dispensing a fluid ( 2 ) and a dosing system for dosing an additive into the fluid ( 2 ). The fluid dispensing system comprises fluid supply means ( 3,8 ), a dispensing nozzle ( 5 ), and a conduit ( 6 ) connecting the supply means to the dispensing nozzle ( 5 ). The dosing system comprises an additive reservoir ( 14 ) for containing the additive ( 12 ) and an outlet ( 22 ) connecting the additive reservoir (14) to the dispensing system. Pumping means ( 8,15,16 ) are provided for pumping the fluid ( 2 ) and the additive ( 12 ) towards the dispensing nozzle ( 5 ). A reliable dosing of additive is achieved in that the outlet ( 22 ) of the additive ( 12 ) communicates with the conduit (6) in a position downstream of said pumping means. A dispensing system for such an appliance is described.

The invention relates to a household appliance according to thepre-characterizing portion of claim 1 and to a dispensing systemaccording to the pre-characterizing portion of claim 17.

Such a household appliances and such a dispensing system are known frominternational patent application WO 99/27176.

Household appliances in which a fluid is dispensed exist in manyvarieties, for example in the form of irons with facilities fordispensing steam and/or water, hair dryers which dispense hot air, airhumidifiers which dispense water and air, or toothbrushes which dispensetoothpaste. The household appliance known from the aforementioneddocument is an iron for ironing textile. In this iron, the fluiddispenser for moistening textile before or during the ironing processcomprises a water reservoir and an additive dosing system for adding anadditive to the water, for example to improve the ironing of the textileor to provide it with a pleasant smell. The reservoir for containing thefluid is a water reservoir. The pumping means for pumping the water andadditive from their respective reservoirs to a mixing chamber aresituated between the water and additive reservoir and the nozzle. In oneembodiment, a separate electric pump for pumping additive is provided inaddition to the electric water pump. In another embodiment, a singlepump pumps water and additive, and two capillaries and an adjustablevalve control the concentration.

Although the separate pumps may enable an accurate and independentcontrol of the respective water and additive flow rates, the use of twoseparate sets of pumping means also brings with it some disadvantages.For example, the application of two separate electric pumps means willadd to the manufacturing cost and will make the appliance more bulky andmore susceptible to mechanical failure. Furthermore, the appliance willbe more complex to operate. In the second embodiment, an accuratecontrol of the concentration is difficult to achieve because thepressure drop across the adjustable valve is relatively small and theviscosity of the additives may vary among additives and with thetemperature of the additive. Furthermore, the capillaries and theadjustable valve form passages with very small cross-sections acrosswhich small pressure drops are applied, so the passages can easily clogup.

It is an object of the invention to provide a solution wherein theabove-mentioned drawbacks are avoided. To that end, a householdappliance as claimed in claim 1 is provided. According to another aspectof the invention, this problem is solved by providing a dispensingsystem as claimed in claim 17.

By positioning the outlet of the additive reservoir such that additivewill enter the conduit downstream of the pumping means, the dosing canbe carried out in a section of the conduit where a substantial pressureis provided by the action of the pump, so that relatively predictablepressure conditions are obtained. Accordingly, the concentration can becontrolled more reliably and the risk of clogging up is reduced.Furthermore, the concentration of additive in the dispensed fluidresponds more quickly to changes in the additive supply rate when theadditive supply is started, stopped, increased or decreased.

In order also to control the supply of additives, the pumping meanspreferably comprise first pumping means for pumping fluid from thesupply means towards the dispensing nozzle and second pumping means forpumping additive from the additive reservoir into the conduit.

To pump additive from the reservoir towards the fluid conduit, thereservoir may be provided with a displaceable or deformable separation,such as a plunger or a membrane. On the side of the separation facingaway from the outlet, pressurizing means may be provided for exerting apressure on said separation, to force additive at the other side of theseparation out of the reservoir.

An inlet passage is provided interconnecting the fluid dispensing systemand a second compartment of the additive reservoir separated from afirst compartment containing the additive by the aforementionedseparation, so that fluid pressure from the dispensing system is guidedinto the reservoir and serves as pressurizing means. Consequently, onlyone pumping device is sufficient for pumping both the fluid to thedispensing nozzle and additive from the additive reservoir to thedispensing system. This results in a simple, compact, and low-costdosing system. A particular advantage of this solution is that thepressure at which additive is being expelled is directly related to thepressure at which the fluid is fed. Hence, the more the pressure atwhich fluid is fed is increased, the more pressure is exerted forexpelling additive. Consequently a very constant additive concentrationis obtained.

It can be ensured in a simple manner that the pressure passed to theinlet is higher than the pressure at the position where the outlet meetsthe fluid conduit in that the inlet connecting the dispensing system tothe first compartment is branched off from the conduit in a positionbetween the first pumping means and the outlet

A desired pressure drop can be generated between the inlet and theoutlet of the additive dosing system for driving additive supply in thata fluid flow restriction is provided in the conduit between the inletand the outlet of the additive reservoir.

Preferably, the fluid flow restriction is adjustable. This offers a userthe option of influencing the pressure drop across the additive dosingsystem reservoir to regulate the additive concentration. Furthermore,the fluid flow restriction is preferably provided with a small leakageflow. Such a leakage flow ensures that, as long as no water isdispensed, the pressure drop across the fluid flow restriction, and thusacross the additive reservoir, will decrease and preferably become zero.This will effectively stop any undesired additive flow.

Inlet flow restriction means may be provided in the inlet, whichconnects the dispensing system to the additive reservoir. These inletflow restriction means affect the pressure drop across the additivereservoir and hence offer an alternative possibility of regulating theflow rate of additive. Such a restriction does not suffer from the riskof clogging up due to caking of additives and from poor predictabilitydue to varying additive flow properties.

The flow of additive towards the fluid conduit can be controlled veryaccurately when the outlet between the additive reservoir and thedispensing system is provided with an outlet flow restriction means.Since a substantial pressure drop is maintained across the outletrestriction, the risk of clogging up is very limited and the sensitivityto variations in flow characteristics of the additive is relativelysmall.

Preferably, the outlet restriction comprises an oscillating valve. Thisis particularly advantageous if the additive to be dosed is veryconcentrated, and very small doses are required to obtain and maintain adesired, constant mixing ratio. Since the cross-section in such a valveis varied constantly, the risk of clogging up and the influence of flowcharacteristics of the fluid are further reduced.

The activation of the outlet flow restriction may be synchronized withthe operation of the first pumping means. Such a synchronization ensuresthat additive is only released when water is being dispensed. Itfurthermore allows for a very simple operation of the appliance,wherein, for maintaining a constant mixture of water and additive, auser can simply operate the pumping means.

The above and other advantageous embodiments of the invention are setforth in the dependent claims.

To explain the invention, embodiments of a household appliance willhereinafter be described by way of example with reference to theaccompanying drawings, wherein:

FIG. 1 is a schematic view of a dispensing system according to a firstembodiment of the invention;

FIG. 2 is a schematic side elevation view of a household appliancecomprising a dispensing system according to FIG. 1;

FIG. 3 is a schematic view of a dispensing system according to a secondembodiment of the invention;

FIG. 4 is a graph depicting the operation of a valve of the systems inFIGS. 3 and 5 in relation to operation of the pump; and

FIG. 5 is a schematic view of a dispensing system according to a thirdembodiment of the invention.

In this description, the same or corresponding parts are designated bymutually identical reference numerals.

FIGS. 1 and 2 show a household appliance in the form of an iron 27 withan ironing sole 28, a handle 29, and a dispensing system 1 fordispensing a first fluid 2. In this example, the fluid is water. Anothercommon fluid dispensable by irons is steam, which is usually dispensedvia the ironing sole 28.

The dispensing system 1 comprises supply means comprising a reservoir 3for containing the water 2 and a pump 8, a conduit 6, and a dispensingnozzle 5. The conduit 6 connects the reservoir 3 to the dispensingnozzle 5. The pump 8 is adapted for pumping the water 2 from thereservoir 3 towards the dispensing nozzle 5. The pump 8 may, forexample, be a piston pump and may, for example, be driven manually or,as is shown in this example, electrically by means of a switch 9. Whenused in an iron, the water can be dispensed onto textile to be ironed,to help eliminating pleats and facilitate the ironing process.

The dispensing system 1 is provided with a dosing system 10, with whichdosing system an additive 12 can be added to the water 2. When used inan iron, the additive 12 may, for example, be an additive for enhancingthe ironing properties or the smell of the textile to be ironed. Thedosing system 10 comprises a second reservoir 14 having a substantiallycylindrical shape. The reservoir 14 is divided into an additive chamber18 and a pressurizing chamber 16 by means of an axially moveable plunger15. A removable lid 17 closes off an open top end of the reservoir 14.When the lid 17 is removed, additive 12 can be filled into the additivechamber 18. The additive is preferably a liquid. Compared with gases andvapors, liquids generally contain a relatively large amount of effectiveingredients and can be handled relatively easily.

The reservoir 14 is connected in parallel to the dispensing system 1 bymeans of an inlet 20 and an outlet 22. The inlet 20 branches off fromthe conduit 6 downstream of the pump 8 and debouches into thepressurizing chamber 16 of the reservoir 14. The outlet 22 is connectedto the additive chamber 18 and communicates with the conduit 6 in aposition downstream of the position where the inlet 20 branches off fromthe conduit 6, preferably at a short distance (less than 2 to 4 cm) fromthe dispensing nozzle 5.

The dosing system 10 furthermore comprises a fluid flow restriction 24and inlet flow restriction means 25 for controlling the flow rate ofadditive 12 into the dispensing system 1. The fluid flow restriction 24comprises an adjustable one-way valve, mounted in the conduit 6 betweenthe inlet 20 and the outlet 22. During operation of the pumping device8, this fluid flow restriction 24 generates a pressure drop ΔP betweenthe inlet 20 and the outlet 22. The inlet flow restriction 25 alsocomprises an adjustable valve, in the inlet 20. With this inlet flowrestriction 25, the flow of water 2 towards the pressurizing chamber 16of the reservoir 14 can be regulated. Together, the pressure drop ΔP andthe flow rate of water 2 into the reservoir 14 determine theconcentration of additive 12 injected into the water dispensed by thedispensing system 1.

The dosing system described above operates as follows. When a useractivates the pump 8, an amount of water 2 is pumped from the reservoir3 towards the dispensing nozzle 5. Part of the water 2 is pumped towardsthe pressurizing chamber 16 of the reservoir 14 through the inlet 20,due to the pressure drop ΔP generated by the fluid flow restriction 24and limited by the inlet flow restriction 25. A portion of the pressuredrop is exerted on the plunger 15, which causes additive 12 in theadditive chamber 18 to be moved into the outlet 22 towards the waterconduit 6. The additive 12 entering the conduit 6 mixes with the waterpassing therein and is subsequently sprayed out via the dispensingnozzle 5.

The inlet flow restriction 25 enables a user to regulate the flow rateof water 2 towards the first compartment 16 and thus the flow rate ofadditive 12 urged to the dispensing system 1. Preferably, the outlet 22is provided with a conical spout 26 which is biased in the flowdirection of the water 2 in the conduit 6, thus enabling a smooth,fluent transition of the additive upon 12 leaving the spout 26 andentering the water 2. Advantageously, the transition trajectory isdesigned such that some turbulence accompanied by a small pressure 5drop exists at or near the point where the additive 12 enters the waterflow. The turbulence makes for a good mixing of the additive and thewater.

By having the additive 12 enter the water 2 at a point near thedispensing nozzle 5, the risk of the subsequent mixture gettingsegregated before being dispensed is minimized.

Preferably, the one-way valve 24 allows a small leakage. This leakageensures that the pressure difference ΔP across the additive reservoir 14will quickly return to zero after the pump 8 has been switched off,preventing an uncontrolled leakage of additive 12.

With a dispensing system described above, the water 2 and additive 12can be pumped, first separately and later combined, towards thedispensing nozzle 5 with one single pump 8. Moreover, during the pumpingthe additive 12 will not contact the pump 8, which prevents the pump 8from getting contaminated and prevents the additive 12 from beingadversely affected by movements and pressures occurring in the pumpingdevice 8. Furthermore, the dosage of additive 12 can be easily andaccurately controlled by adjustment of the inlet flow restriction 25.Also, the additive dosage is related to the water supply pressure andthus to the amount of water being fed by the pump 8. Hence, fluctuationsin the water supply will cause similar fluctuations in the supply ofadditive 12 to the water 2, as a result of which the overall compositionof the fluid-additive mixture will remain very constant, without anyneed for the user to interfere.

FIG. 3 shows an alternative embodiment of a dosing system 10 accordingto the invention, in which an outlet flow restriction 30 is provided inthe outlet 22 for regulating the flow rate of additive 12 towards theconduit 6. The inlet flow restriction means 25 illustrated in FIG. 1 areomitted. The outlet flow restriction 30 is provided in the form of anoscillating valve. Furthermore, a mixing chamber 32 is provide where theoutlet 22 meets the conduit 6.

With the oscillating valve 30, the flow rate of additive 12 towards theconduit 6 can be very accurately controlled at a constant, desiredvalue. This is advantageous, for example, if the additive is highlyconcentrated and small amounts of additive need to be dosed.

Preferably, the activation of the oscillating outlet flow restriction 30is coupled to the operation of the pumping device 8 so that oscillationstops and the valve is closed when the pump 8 stops and oscillationstarts when the pump starts, as is illustrated by FIG. 4. This ensuresthat no additive 12 gets spoiled once the pumping means 8 and thedispensing of water 2 are stopped.

The mixing chamber 32 allows the additive 12 and the fluid 2 to be mixedto a homogenous mixture, to be dispensed by the nozzle 5.

It is observed that providing the restriction in the inlet or the outletis advantageous for preventing or at least reducing overdosage atstart-up of the fluid flow. When the fluid flow is started, the pressurebuild-up precedes the increase of the flow rate to equilibrium at thegiven pressure. Since the flow rate of the additive 12 is relativelylow, the additive flow reaches a flow rate in the range of the flow rateduring constant operation more quickly than does the fluid flow.

FIG. 5 shows a third embodiment of a dosing system 10 according to theinvention, in which the driving means for driving the additive 12 out ofthe additive chamber 18 are formed by a spring 35 mounted on the side ofthe separation 15 facing away from the additive chamber 18. The springco-operates with the plunger 15 in forcing additive 12 contained in thesecond compartment 18 towards the outlet 22 and into the conduit 6. Asin the embodiment shown in FIG. 3, the flow restriction 30 is providedin the outlet 22 towards the water conduit 6. The outlet flowrestriction 30 allows the outlet to be shut off completely when the pump8 is inoperative, so the flow rate of additive can be stopped completelyeven in a situation in which the feeding pressure on the additive 12 ismaintained even while the pump 8 is inoperative. As in the previouslydiscussed embodiment, a mixing chamber 32 is provided for mixing theadditive and the fluid before they are dispensed by the dispensingnozzle 5.

By using a spring 35 as the pressurizing means, a simple drive structurefor driving additive to the conduit 6 is obtained. Moreover, all pumpingcapacity of the pump 8 is available for pumping the water 2 towards thedispensing nozzle 5.

The invention is not limited to the embodiments as described. Forexample, the flow restrictions may be embodied by other types of valvesthan those described above. When applied in an iron, the additivereservoir as well as the water supply means and in particular the fluid(water) reservoir may be disposed at least partly outside the iron. Theadditive may also be dosed into fluids other than water, for exampleinto steam dispensed by the iron, or into air. The appliance may be anyappliance from which fluids are dispensed, such as hair dryers, airhumidifiers, coffee makers, or toothbrushes.

1. A household appliance comprising a fluid (2) dispensing system fordispensing a fluid (2) and a dosing system for dosing an additive (12)into said fluid (2); said fluid (2) dispensing system comprising fluidsupply means (3, 8), a dispensing nozzle (5), and a conduit (6)connecting said supply means to said dispensing nozzle (5); said dosingsystem comprising an additive reservoir (14) for containing the additive(12) and an outlet (22) connecting the additive reservoir (14) to thedispensing system; and said fluid supply means comprising pumping means(8, 15, 16, 20, 35) for pumping the fluid (2) and the additive towardsthe dispensing nozzle (5); characterized in that the outlet (22) of theadditive reservoir (14) communicates with the conduit (6) in a positiondownstream of said pumping means (8, 15, 16,20, 35).
 2. An appliance asclaimed in claim 1, wherein the pumping means (8, 15, 16, 35) comprisefirst pumping means (8) for pumping fluid (2) from the supply meanstowards the dispensing nozzle (5) and second pumping means (15, 16, 20,35) for pumping additive (12) from the additive reservoir (14) to theconduit (6).
 3. An appliance as claimed in claim 2, wherein the secondpumping means comprise driving means (16, 20, 35) and a displaceable ordeformable separation (15) bounding an additive chamber (18) of theadditive reservoir (14) for receiving the additive (12), the drivingmeans (16, 20, 35) being adapted for exerting a driving force on saidseparation (15) for forcing additive (12) out of said chamber (18)through the outlet (22) towards the conduit (6).
 4. An appliance asclaimed in claim 3, wherein said driving means comprise an inlet (20)and a pressurizing chamber (16) of the reservoir (14) on a side of saidseparation (15) facing away from the additive chamber (18), said inlet(20) interconnecting said pressurizing chamber (16) and said conduit (6)for applying fluid (2) pressure from the conduit (6) to said separation(15).
 5. An appliance as claimed in claim 4, wherein said inlet (20)branches off from the conduit (6) in a position between the firstpumping means (8) and the outlet (22).
 6. An appliance as claimed inclaim 5, further comprising a fluid flow restriction (24) in the conduit(6) between said inlet (20) and said outlet (22) for generating apressure drop between said inlet (20) and said outlet (22).
 7. Anappliance as claimed in claim 4, further comprising an inlet flowrestriction (25) in the inlet (20) for adjusting the flow rate of fluidtowards the pressurizing chamber (16).
 8. An appliance as claimed inclaim 1, further comprising an outlet flow restriction (30) in theoutlet (22) for controlling the flow rate of additive towards theconduit (6).
 9. An appliance as claimed in claim 3, wherein the drivingmeans comprise a spring (35).
 10. A dispensing system for dispensing afluid (2) and an additive (12) from a household appliance, comprisingfluid supply means (3, 8), a dispensing nozzle (5), a conduit (6)connecting said supply means (3, 8) to said nozzle (5), pumping means(8, 15, 16, 20, 35) for pumping the fluid (2) from said supply meanstowards said dispensing nozzle (5), an additive reservoir (14), and anoutlet (22) connecting the reservoir (14) to the conduit (6),characterized in that the outlet (22) of the reservoir (14) communicateswith the conduit (6) in a position downstream of said pumping means (8,15, 16, 20, 35).